The effects of temperature, pH, and sediment on the fate and toxicity of 1‐naphthol to the midge larvae Chironomus riparius

Abstract

The effects of temperature, pH, sediment and humic acid on the toxicity and fate of 1‐naphthol to the midge larvae, Chironomus riparius, were determined in static 24‐hr toxicity tests. Partitioning of ¹⁴C‐1‐naphthol in systems identical to toxicity tests was examined to determine if toxicity results were supported by physical‐chemical measurements. Generally, 1‐naphthol toxicity increased with increasing temperature. Changes in pH did not affect toxicity except at pH 8 where 1‐naphthol was more toxic to the midge at 10 and 20 °C than at pH 4 or 6. In addition, there was no temperature effect at pH 8 as naphthol was equitoxic at all temperatures. The presence of sediment reduced toxicity in the temperate range (20–30 °C ) while humic acid had no effect on toxicity at any temperature. Partitioning data did not always support toxicity results, illustrating the importance of coupling bioassays with physical‐chemical studies when evaluating water soluble chemicals.